<?php
$dt = new DateTime();
$dt->setTimestamp(3.4); // I replaced 3.4 by microtime(true), this is just to give an example
var_dump($dt);
var_dump($dt->format('u'));
Deprecated: Implicit conversion from float 3.4 to int loses precision in /in/hPVdT on line 4
object(DateTime)#1 (3) {
["date"]=>
string(26) "1970-01-01 01:00:03.000000"
["timezone_type"]=>
int(3)
["timezone"]=>
string(16) "Europe/Amsterdam"
}
string(6) "000000"